Off position retainable door operated electric switch



A ril 26, l 6 5 A.A. HIRSCH OFF POSITION RETAINABLE DOOR OPERATED ELECTRIC SWITCH Filed Jan. 14, 1963 INVENTOR United States Patent 3,179,766 OFF POSITION RETAINAIILE DOOR {)PETED ELECTRIC SWITCH Abraham Adler Hirsch, 141 Norwood St., Shreveport, La. Filed Janll4, 1963, Ser. No. 251,445 1 (Ilaim. (Cl. ZOO-61.81)

My invention relates to a door operated electrical switch, such asused for turning on and off the dome light, glove compartment light or similarly controlled lighting circuits in automotive or other low voltage uses. Ordinarily such lights are turned on incidentally when the door is opened, and off when the door is closed. If the door is left open, the light continues to burn. This tends to drain a weak battery. At other times it may be desirable to avoid lighting up the interior of a car every time the door is opened. While it is possible to include an off-on manual switch connected in series in the circuit to the dome light, a more compact, self-contained and eiiicient switching device is desirable.

Myimprovement consists in designing the door operated switch in such a manner that by simply rotating the plunger a part of a turn while in the depressed or off position, the plunger will be so retained and switch re mains permenanently off. This retention feature for the off, position is obtained by providing a set of prongs on the switch front plate and a corresponding set of splines or grooves on the plunger. These terminate short of the front of the plunger where the diameter is reduced to permit complete rotation of this part between the prongs. When the plunger, in the off position is turned so that the splines do not register with the prongs, the switch is held in this position. The structure and mode of operation of this improvement is illustrated in the following drawings in which:

FIGURE 1 is a cross section of the assembly of a typical door-operated dome light switch for automobiles which has been modified to permit retaining an off position setting when so desired,

FIGURE 2 is an elevation of the plunger of the above switch as modified to keep an off setting,

FIGURE 3 is a section of the plunger along line a-a of FIGURE 2,

FIGURE 4 is a front view of the plunger,

FIGURE :5 is an elevation of the front plate of the switch as revised to hold an off setting.

FIGURE 6 is a section of FIGURE 2 along the line bb with the plunger in the operating position; a portion of the front plate is added to show its cooperative function, and

FIGURE 7 is the same section as in FIGURE 6 but with the plunger turned in the hold off position.

Identical reference numerals in the different views indicate the same structural element. Referring to the separate drawings:

FIGURE 1 shows an assembled door-operated switch in section. Face plate 1 is attached to the cylindrical shell 2. The joint may be spot welded, rolled or folded. Back plate 3 is held to the rear of the shell by a fold over piece 4. This back plate is a non-conductor. Inside of the shell is an insulating plunger 5 having a Wide piston 6 at its rear over which fits a fairly thin metallic cover or thimble 7. This cover has pimples 8 to make good conductive contact with the inside of the shell. A helical spring 9 pressing between the back plateand the metal conductor 7 normally keeps the plunger extended to the right of its travel. A cylindrical bore 10 extends almost through'the length of the plunger, as shown. Inside channel 10 extends a contactor rod 11, made of springy metal, terminating in a spoon shaped contacting point 12 which presses against the wall inside of the bore of the plunger.

At the rear plate of the switch conductor 11 is attached to a terminal bolt 13. Two nuts 14 are screwed on bolt 13, the inside one to hold the screw tightly against the rear plate and the outside nut to allow electrical connection, Front plate 1 has an upper and a lower hole 15 to enable the assembly to be screwed or bolted to a door frame.

In operation the plunger is in the fully depressed position whenever the door is closed. In this state the conductor rod 11 touches only the insulating material of the plunger, and no current flows through the switch to the dome light. On the other hand, when the door is opened the compression spring 9 pushes the plunger to the extreme right or on-position. In this case the conductor rod touches the inside of the metal thimble 7, thereby grounding the dome light circuit through the cylindrical shell and face plate to the door frame of the car. With previous switches, the dome light burned so long as the car door remained open. To this point only the prevailing art has been described operatively.

The novel construction of subject switch consists in adding a set of longitudinal grooves or splines 16 along the shaft of the plunger, and decreasing the diameter at the front of the plunger to form a reduced section 17. Also a set of prongs 18 is provided on the face plate 1. These permit the plunger to move forward or backward only when properly lined up with the grooves.

The elevation view of the plunger, FIGURE 2, shows the grooves 16 along the shaft extending from the piston 6 to the reduced diameter 17 at the tip. Flats have been formed on opposite sides of the tip to facilitate gripping by a persons fingers when rotating the plunger.

FIGURE 3 showing the barrel of the plunger in section, illustrates the position of the grooves.

In the front view of the plunger, FIGURE 4, the grooves are shown extending to the front of the shaft. The reduced tip 17 is shown with flat 19. The smaller diameter at the tip permits this section to be rotated between prongs 18.

FIGURE 5 shows a face plate in which to the central hole 20 has been added 2 oppositely placed prongs 18 across a diameter.

FIGURES 6 and 7 show the relative position of the grooves and front tip with respect to the prongs in the fully expanded or off position, and fully compressed or off position, respectively. In FIGURE 7 the prongs fail to register with the grooves thereby restraining the plunger compressed within the shell.

Although the description deals with a front plate and splined plunger having 2 prongs and grooves, respectively, other numbers of these features may be used. Also since there may be free play radially between the plunger, when fully compressed, and the joint between the front plate and the cylindrical shell according to mode of fabrication forming a burr or lip, the shoulder behind the flats of the front of the plunger may be made to catch on such burr or lip to effect a retention in the oif position. However, this possibility is not considered to be a preferred method.

I claim:

A latchable door-operated low voltage light switch consisting of a cylindrical metallic shell which contains the parts thereof, a front plate for closing the front end of said shell and providing a mounting means within a door jamb, a rear plate for closing the back end of said shell, a plunger and a piston integral therewith made of insulating material movable coaxially within said shell, a bore running through said piston almost the length of said plunger, a thin metallic thimble lining the inside of said piston and also contacting said cylindrical shell, a contacting rod leading from a binding post on said rear plate to make contact with said thimble and close the lighting circuit when said door is opened and extend into said bore within said plunger when said door is shut thereby breaking said lighting circuit and cooperative latching means on said plunger and said front plate to retain said plunger in the ofi position permanently when desired, said latching means consisting of a pair of longitudinal grooves along the length of said plunger parallel to the travel thereof, prongs in said front plate to match into said grooves and permit slidable movement of said plunger, a front tip on said plunger having a reduced diameter so as to permit free rotation between said prongs when said plunger is depressed, flats formed on opposite sides of said tip to enable a finger grip for rotation, a shoulder at the back of said tip, said shoulder holding the switch in the off position when said plunger is depressed and rotated so that said grooves fail to register with said prongs on said front plate, said spring urging said shoulder against said prongs in the ofi position, said switch being in an operable position to turn on or off with the opening and closure, respectively, of said door when said plunger is turned so that said grooves align with said prongs on said front plate.

References Cited by the Examiner UNITED STATES PATENTS 2,592,660 4/52 Crumley 200-159 2,717,295 9/55 Marvin ZOO-61.79 2,810,061 10/57 Serrone ZOO-61.79 2,875,290 2/59 Shattow 200-169 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

